Technical Field
The present disclosure relates to an apparatus for treating spinal conditions, and more particularly, to an intervertebral implant and a method of use therefor.
Background of Related Art
The human spinal column is a highly complex structure. It includes twenty-four discrete bones, known as vertebrae, coupled sequentially to one another to house and protect critical elements of the nervous system. The vertebrae interlock with one another to form a spinal column. Each vertebra has a cylindrical bony body (vertebral body), two pedicles extending from the vertebral body, a lamina extending from the pedicles, two wing-like projections extending from the pedicles, a spinous process extending from the lamina, a pars interarticularis, two superior facets extending from the pedicles, and two inferior facets extending from the lamina.
The vertebrae are separated and cushioned by thin pads of tough, resilient fiber known as inter-vertebral discs. Inter-vertebral discs provide flexibility to the spine and act as shock absorbers during activity. A small opening (foramen) located between each vertebra allows passage of nerves. When the vertebrae are properly aligned, the nerves pass through without a problem. However, when the vertebrae are misaligned or a constriction is formed in the spinal canal, the nerves get compressed and may cause back pain, leg pain, or other neurological disorders.
For many reasons, such as aging and trauma, the intervertebral discs can begin to deteriorate and weaken, potentially resulting in chronic pain, degenerative disc disease, or even tearing of the disc. Ultimately, the disc may deteriorate or weaken to the point of tearing and herniation, in which the inner portions of the disc protrude through the tear. A herniated disc may press against, or pinch, the spinal nerves, thereby causing radiating pain, numbness, tingling, and/or diminished strength or range of motion.
Many treatments are available to remedy these conditions, including surgical procedures in which one or more damaged intervertebral discs are removed and replaced with a prosthetic. After a partial or complete discectomy, the normally occupied space between adjacent vertebral bodies is subject to collapse and/or misalignment due to the absence of all or part of the intervertebral disc. In such situations, the physician may insert one or more prosthetic spacers between the affected vertebrae to maintain normal disc spacing and/or the normal amount of lordosis in the affected region.
Typically, a prosthetic implant is inserted between the adjacent vertebrae and may include pathways that permit bone growth between the adjacent vertebrae until they are fused together. However, there exists a possibility that conventional prosthetic implants may be dislodged and moved from their desired implantation location due to movement by the patient before sufficient bone growth has occurred.
Bone growth is a key factor in ensuring adequate retention of the implant to the vertebra. Specifically, bone ingrowth within and around the prosthetic implant promotes fusion between the adjacent vertebra, thereby strengthening the joint therebetween. However, conventional implants do not allow optimal space for bone ingrowth. In these instances, as the prosthetic implants do not mimic bone density of the adjacent vertebra, the body rejects the implant, and non-union (i.e., no fusion) occurs.
Conventional prosthetic implants are typically constructed in a manner that inhibits bone ingrowth, particularly those that include no spaces or avenues for such bone growth to occur within and around the prosthetic implant. The lack of fusion may allow the implant to become dislodged or moved from its desired location. Additionally, in the instances where the prosthetic implant includes a lumen for the packing of ingrowth material, the material is often able to dislodge from the lumen, and in some instances, from the implant, thereby reducing the chances that adequate bone ingrowth occurs.
Therefore, a need exists for a prosthetic implant that can mimic the density of bone or adequately retain ingrowth material therein to allow for optimal bone ingrowth and provide a solid fusion of the vertebral segments.